Radial aircraft engine



RADIAL AIRCRAFT ENGINE Filed Sept. 1, 1944 2 sheets-slim 1 L aae newOPDE? AND VALVE owe-e241:

. I Inv'eulare du aal'uu flqwawuck Sept} 1947. A.\HASBROUCK ET AL v 73RADIAL AIRCRAFT ENGINE I Filed Sept. 1, 194A 2 Sheets-Sheet 2 lzven'tbrs dilga'zstus Kasai-0% die Patented Sept. 2, i947 2 7 STTESPATENT OFFICE RADIAL AIRCRAFT ENGINE Augustus Hasbrouck, Middletown,Alexander H. King, West Hartford, and Lewis Morgan Porter and George L.Williams, Manchester, Conn, assignors to United Aircraft Corporation,East Hartford, Conn, a corporation of Delaware Application September 1,1944, Serial No. 552,369 4 Claims. (Cl. 123-55) This invention relatesto multi-row radial airprovides exceptionally good distribution of thecraft engines. charge among the cylinders of each bank as well An objectof this invention is to improve the as among all the cylinders of theengine, as a operational characteristics of aradial engine havwhole, andenables the intake manifolds to be ing circumferential rows andlongitudinal banks 5 made of minimum weight and of minimum reofcylinders by providing-a novel charging and firsistance to the flow ofcharging air or fuel-air ing arrangement for the cylinders of such anmixture. engine. Referring to the drawing,Fig. 1 shows abank of Afurther object of this invention is to improve cylinders constitutingone. of the cylinder banks the charging characteristics of a four rowradial marked l to l in Figs. 2 and 4'. The cylinders aircraftenginehaving banks of cylinders, by sup- 2 l5 are mounted on thecrankcase 34 in four cirplyingeach bank of cylinders with charging fluidcumferential rows around the crankcase. Pisthrough an inline or gallerytype manifold and tons (not shown) in the cylinders. 2| 5 are con byfiring the cylinders of the bank progressively nected by articulatedconnecting rod systems at equal intervals from one to the other end ofincluding master rods 201, 209, 2H and 213 to the the cylinder bank.crankshaft 58, which in turn is connected to Other objects andadvantages will be apparent the propeller 3| by a reduction gear drivein the from the specification and claims, and from the nose 30. Thebanks l to I extend spirally or heliaccompanying drawing whichillustrates what is cally on the crankcase and all the cylinders are nowconsidered to be a preferred embodiment of equally angularly spacedaround the crankcase as the invention. shown in Figs, 2 and 5.

In the drawings: Each bank of cylinders is provided with a single Fig. 1is a top view of a single bank of cylinders induction pipe or gallerytype manifold 22 (Fig. including ignition and chargin means therefor. 1)disposed between the oppositely extending in- Fig. 2 is a developed viewof an engine con- 25 take rocker boxes 220 and exhaust rocker boxesstructed according to this invention, showing 2l8 and xtending from thesup t t schematically the cylinder, manifold, and super- 2 5alO g the pf the bank to. the intake port charger arrangement. 22.2 of the front.cylinder of the bank. The intake Fig. 3 is a chart showing the cylinderfiring ports 222 of the remaining three cylinders in the order andintake valve timing. bank are connected to outlets in the side of theFig. 4 is an isometric schematic view of an enmanifold 224, and thus allthe cylinders of the gine with which this invention is particularly bankare supplied with chargin l 1' fuel and adapted f use, air from a singlepipe having a direct connec- Fig. 5 is a, diagram showin the spacing ofthe tion with the collector ring of the supercharger. axes of thecylinders of Fig. 4, and their rela- The manifold 22.4 is preferablymade in sections, tion to the spacing of the crankshaft throws. ch h vina ran h or side outlet for con- Figs. 6 and 8 are schematic side andrear views necticn to One f the ports and Whi h are of the crankshaft.joined by flexible connections 239 to form a single Fig. 7 is aschematic isometric View of the p pe. k t, The supercharger, which ispreferably of the Figs. 9 and 10 are schematic side and rear viewscentrifugal typ iS schematically p e d n of the crankshaft, showing amodification of the ig. 2 and has an annular collector-ring P crankshaftcounterweighting. vided with. equally angularly spaced outlets 226, toAccording to this invention, the cylinders of which the various intakemanifolds 224, are coneach bank of a four row, seven bank engine ofnected. Charging air or fuel-air mixture is adthe type disclosed in theHobbs-Willgoos a plicamitted to the supercharger by an axial centralintion Serial No. 552,372, filed concurrently heret p s d at fr m w i hhar i fluid with, are fired at equal intervals, progressively is forcedly by an impel (not shown) to from one end to the. other end of eachbank. In the n r collector g schematically r p addition, the cylindersof the engine as a Whole Sentecl at are fired at equal intervals. It hasbeen found Each bank of y s-is pr v d W t i it on that this firingorder, when used in combination mechanism including a magneto H6 and anigwith a gallery manifold, or a single induction pipe nition manifold II! from which branch ignition for each bank fed from one end andconnected leads H9, l2l, I25, I21 extend to the respective with shortbranches to each cylinder of the bank, cylinders of the banks. Rockerboxes 22!], and

2 I8 are provided which enclose poppet type valves actuated by valvemechanism (not shown). Reference is made to the Hobbs-Willgoosapplication Serial No. 552,372, filed concurrently herewith, for adetailed disclosure of the ignition and valve mechanism, which are notper se a part of this invention.

The engine crankshaft 58 has four crankpins I12, I14, I16, I18 withadjacent crankthrows psitioned on opposite sides of the crankshaft axisand with the throws being angularly offset progressively from one to theother end of the crankshaft by an amount equal to the angle of offset ofthe successive cylinders of any one bank, as shown in Figs. 4 to l0.-The crankshaft may be balanced by a pair of counterweights as shown inFigs. 6 and 8, of this pair of counterweights may be split to providethe four counterweight arrangement shown in Figs. 9 and 10.

The ignition mechanism and the valve mechanism are so timed relative tothe rotation of the crankshaft as to fire the cylinders in the sequenceillustrated in Fig. 3. Cylinder A is fired immediately after cylinder D!and then come cylinders B2, C6, D3, A1, etc. as shown in the chart. Thecylinders are fired at equal intervals of time and as the engine is ofthe four cycle type there will be fourteen equal firing intervals foreach revolution of the crankshaft. Fig. 3 therefore represents twocrankshaft revolutions.

The cylinders are not only fired at equal intervals' for the engine as awhole but are also fired at equal intervals among the cylinders of eachbank. Furthermore, the cylinders of each bank are fired progressiveldown the bank; for instance, bank I fires DI, CI, Bl, Al, DI. Thisfiring order has been found to provide exceptionally good distributionof the charge among the various cylinders of each bank, particularlywhen used in combination with a gallery manifold of the type shown. Italso provides other advantages, particularly when used with an engine ofthe type shown for instance, the firing impulses are equall spaced andthe crankshaft torque peaks are therefore uniformly spaced, therebyproviding an exceptionally smooth running engine. As stated above, thecylinders of each bank are not only fired progressively down the bankbut are also fired at equally spaced intervals among the cylinders ofthe engine as a whole. Referring to Figs. 3 and 5, cylinder Cl fires atseven intervals after cylinder Di, cylinder Bl fires at seven intervalsafter cylinder Cl, cylinder Al is fired, at seven intervals aftercylinder BI, and cylinder D! is again fired at seven intervals aftercylinder Al. Consequently, a complete engine bank can cut out or berendered inoperative with minimum effect upon smoothness of operation ofthe engine. For instance, if one of the magnetos I I6 would fall, so astojcut off the ignition supply to the cylinders of the correspondincylinder bank, the engine would still continue to run quite smoothlybecause the cylinders that would stop firing due to such a failure wouldhave their firing intervals equally spaced among the firing intervals ofthe othercylinders and consequently would have minimum effect on thesmoothness of engine operation. This is particularly important in anaircraft engine having separate ignition systems and manifold systemsfor each, cylinder bank, In such an engine, with the firing order shownin Figs. 3 and 5, one or more banks may cut out due to mechanicalfailure or similar reasons. yet the other banks will continue tofunction in their normal manner.

.4 Thus, each bank functions to a large extent as a separate engine,which considerably increases the dependability of the engine as a wholeand materially increases aircraft safety.

The intake valve timing for each bank is particularly important with thefiring order described above. It is shown at the bottom of Fig. 3, inwhich the line 261 represents the point CI, Bi and Al, respectively,close.

at which the intake valve of cylinder Di opens, while the lines 263, 265and 28'! represent the times at which the intake valves for cylindersCi, BI and Al, respectively, open. Line 283 represents the time at whichthe intake valve of cylinder DI closes, and lines 285, 281, 23Lrepresent the time at which the intake valves of cylinders The intakevalve of each cylinder opens 20 before top dead center and closes 76after bottom dead center, consequently there will be an overlap (theintake valves of two cylinders being open simultaneously) between theintake valves in different cylinders of the same bank during an intervalof 96. Each valve will be open during an interval of 276 and the intakevalve of one cylinder will open 96 before the intake valve of thecylinder immediately preceding in firing order closes. Charging fluidwill, therefore, be passing simultaneously to two cylinders of each bankduring the opening and closing periods of valve movement, but during thefully open valve periods only one valve will be open and the chargingfluid will be admitted to only on cylinder. For example, when the enginecrankshaft is in a position in which the intake valve of the cylinder D!is fully open charging fluid will be passing only to that cylinder. Asthe intake valve of cylinder Dl begins to close the valve of cylinder Clwill open and charging fiuid will be admitted to both cylinders Di andC! until the valve of cylinder DI is closed. As the valve of cylinder Clbegins to close the valve of cylinder BI opens and charging fluid willbe admitted to both cylinders Cl and BI until the valve of cylinder CIis closed. This process is repeated among all the cylinders of the bankin the manner shown at the bottom of Fig. 3. The airflow from the bloweroutlet 22$ to the Various cylinders of the bank is always in onedirection and by the shortest path and it has been found that with thefiring order and valve overlap shown in Fig. 3 and with the manifoldarrangement shown in Fig. 1 that the cylinders of each bank will beuniformly charged to provide equal distribution of power output anduniformity of operation among the cylinders of each bank. Furthermorewith the combination shown in Fig. 2 by which each intake manifold issimilarly connected to the supercharger collector 232, at equal angularspacings, the charge distribution among the various banks is alsouniform and provides uniform power output and operation among thecylinders of the engine as a whole.

Reference is made to our applications Serial No. 552,368 and Serial No.552,370, filed concurrently herewith, which claim subject matterdisclosed and not claimed in this application.

The word longitudinal is used in a broad sense in this application toinclude cylinder banks extending generally lengthwise.

It is to be understood that the invention is not limited to the specificembodiment herein illustrated and described. For instance, it may beused in engines having five or nine longitudinal banks, or more thanfour circumferential rows,

or in other ways without departure from its spirit as defined by thefollowing claims.

We claim:

1. In a radial aircraft engine having a crankshaft, a plurality ofcylinders spaced equally around said crankshaft and arranged in fourcircumferential rows and seven spiral banks with four cylinders in eachbank, an intake opening in the top of each of said cylinders, aninduction pipe extending along the top of each cylinder bank and havingfour outlets respectively connected with the intake openings of thecylinders in the bank, said induction pipes each having a single inletat one end thereof, and means for firing the cylinders in each 0f saidbanks at equal intervals during two revolutions of said crank shaftsuccessively from the end of the bank farther-most from its inductionpipe inlet to theend of the bank closest to said induction pipe inlet.

2. The combination of claim 1, including an intake valve for controllingthe flow of fluid through each of said intake openings, With the valvesin successively firing cylinders having overlapping open periods.

3. In a radial aircraft engine, a plurality of cylinders arranged infour circumferential rows and in longitudinal banks, and means forfiring said cylinders at equal intervals for the engine as a whole andat equal intervals for each bank, with the cylinders of each bank beingfired progressively from one to the other end of said bank, successivelyfiring cylinders of the engine as a Whole being located about onehundred and eighty degrees apart.

4. In a radial aircraft engine having cylinders arranged incircumferential rows and in longitudinal banks, a separate gallery typemanifold for each bank comprising a single induction pipe extendingalong the bank and having a plurality of outlets respectively connectedwith intake openings in the cylinders of the bank, each induction pipehaving a single inlet at one end thereof, means for firing the cylindersof the engine as a whole at equal intervals and for firing the cylindersin each bank at equal intervals consecutively from one to the other endof said bank, and an intake valve in each cylinder for controlling theflow of fluid through the respective intake opening, with the valves ofsuccessively firing cylinders in each bank having overlapping openperiods.

AUGUSTUS HASBROUCK.

ALEXANDER H. KING. LEWIS MORGAN PORTER. GEORGE L. WILLIAMS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,283,970 Thomas Nov. 5, 19182,366,852 ,Goodman Jan. 9, 1945 1,367,194 Lefranc Feb. 1, 1921 1,241,199Crompton Sept. 25, 1917 2,120,045 Towns June 7, 1938

